In a conventional projector system, there is typically a single light source that illuminates a screen with an image that is modulated by some optical system within the projector. When there is an image to be projected that has a “highlight” (that is, a region of high brightness e.g., a specular reflection off of a surface in the image, direct sunlight, a luminant object, one region that is substantially more luminant than other regions or the like), then the highlight would have the same luminance level as the “full” screen. In that case, the light coming through the projector would have to be fully ON for the entire screen and the projector system would have to “throw away” light that is not a part of the highlight. This may not tend to be the most-efficient use of the light source.
To address some of these inefficiencies, dual or multi-modulator projector systems are being proposed as a novel way of projecting images and video.